Exercise is performed as 2 weeks one-legged training on an ergometer bicycle. Thus one leg serves as a control leg. Insulin sensitivity in trained and non-trained muscle will be measured after completion of the overall training program by euglycemic hyperinsulinemic clamp method and a-v catheterization of both legs. Muscle biopsies will be obtained during training period for measuring of muscle glycogen content, and muscle biopsies for further analysis obtained during the experimental day.